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For years, when researchers talked about the enzymes that damage the vaginal mucous barrier in bacterial vaginosis (BV), they mostly pointed at one culprit: Gardnerella. A 2024 study in PNAS says that picture has been missing a major player.
That player is Prevotella, a group of disruptive bacteria that turns out to be a leading source of the sialidase enzymes linked to BV and its complications.1
It is a small word with big consequences, so here is what sialidases are, why they matter, and what this finding changes in BV.
What are sialidases, and why should you care?
Sialidases are enzymes that snip sugar molecules called sialic acids off the surface of your cells and your protective mucous.1
That mucous layer is part of your defence. It traps unwelcome microbes and keeps the vaginal lining protected. When sialidases strip it back, the barrier thins, and that is bad news.1
High sialidase activity is one of the recognised hallmarks of BV, and it has been tied to a higher risk of complications, including preterm birth and a greater susceptibility to other infections.1
Why did researchers look beyond Gardnerella?
Until this study, the sialidases that had actually been pulled apart and studied in the lab came from Gardnerella. Other vaginal bacteria were assumed to matter less, partly because no one had characterised their enzymes.1
The team, led by researchers at Harvard, decided to test that assumption. They identified candidate sialidase genes in several Prevotella species, produced the enzymes in the lab, and confirmed they were genuinely active.1
What did the Prevotella study find?
Across real vaginal samples, sialidase genes and their active transcripts from Prevotella, especially Prevotella timonensis, were more prevalent and more abundant than those from Gardnerella.1
In other words, when you measure what is actually being switched on and used in the vaginal environment, Prevotella looks like a predominant source of sialidase activity, not a bit-part player.1
The enzymes chew through mucous and antibodies
The Prevotella sialidases released sialic acid from a range of targets, including mucins (the building blocks of protective mucous) and immunoglobulins such as IgA and IgG, the antibodies that patrol cervical mucous.
Different Prevotella enzymes varied in how aggressively they attacked mucins, which hints at a division of labour between species.1
A flu drug switched some of them off
Intriguingly, the antiviral flu drug zanamivir (Relenza), which is designed to block a sialidase made by influenza, also blocked the sialidases from P. timonensis, though not those from other species. It is far too early to call that a treatment, but it is a tantalising lead for future drug targeting.1
Why this matters for BV treatment and testing
BV is increasingly understood as a community problem rather than a single-organism infection, and this study reinforces that. If you focus only on Gardnerella, you may be missing a big chunk of the enzyme activity that damages the protective barrier.1
This fits how we approach stubborn BV at My Vagina. Effective treatment usually means tackling the whole disruptive community and the biofilm that shelters it, not chasing one organism.
Targeted antimicrobials such as our unhique BV-Prevella Clear blend and biofilm-disrupting support, paired with measures to restore protective bacteria, are aimed at exactly that broader picture, alongside systemic support to address the underlying drivers.1
Frequently asked questions
Is Prevotella worse than Gardnerella?
Not worse, but more important than previously thought. This study found Prevotella sialidase genes and transcripts were more prevalent and abundant than those from Gardnerella across vaginal samples, which means it deserves more attention in BV than it has historically received.1
What does sialidase activity have to do with my symptoms?
Sialidase enzymes break down the protective mucous layer and even some of your antibodies. High sialidase activity is a marker of BV and is linked to complications, which is why some clinical tests measure it.1
Can I take a flu drug to treat BV?
No. The zanamivir finding is a laboratory observation about enzyme inhibition, not a treatment recommendation. Please do not self-treat BV with antiviral medication.1
What to do next
If BV keeps returning, the takeaway is to treat the whole disruptive community, not just one named bacteria.
- Find out which bacteria are involved with a thorough PCR or NGS microbiome test.
- Treat the whole disruptive community, including Prevotella (and the species now reclassified as Hoylesella), with targeted antimicrobial and biofilm support.
- Support protective bacteria as part of treating the whole community, not just one organism.
Related Posts
References
- Pelayo P, Hussain FA, Werlang CA, et al. Prevotella are major contributors of sialidases in the human vaginal microbiome. Proceedings of the National Academy of Sciences. 2024;121(36):e2400341121. Full text
